The Avenger, by Matthew Blood (epub/Kindle/pdf)

Morgan Wayne knew that the peddlers of vice and dope were untouchable.

He knew that the Mafia's arm was long and its hand held a killer's knife.

He knew the willing women they would send to tempt and betray him.

He knew his own nerve and strength and skill.

He knew the white hate within him for the crime lords and their gunmen.

So he walked alone into the very heart of gangland to deal justice where the law had failed.